Universal Gravitation
1) What factors affect the weight of an astronaut during a rocket flight? How does the astronaut’s weight
change?
2) Which diagram best represents the gravitational force acting on you and on Earth? Explain your reasoning.
3) How could you distinguish between a 5.0-kg medicine ball and a basketball in outer space without looking at
both objects?
4) Two people, A and B, are sitting on a bench 0.60 m apart. Person A has a mass of 55 kg and person B a mass
of 80 kg. Calculate the magnitude of the gravitational force exerted by B on A. (8.2 x 10-7 N)
5) Mount Logan in the Yukon is 5959 m above sea level, and is the highest peak in Canada. Earth’s mass is 5.97
x 1024 kg and Earth’s equatorial radius is 6.38 x 106 m. What would be the difference in the magnitude of the
weight of a 55.0-kg person at the top of the mountain as compared to at its base. Assume that Earth’s
equatorial radius is equal to the distance from Earth’s centre to sea level. (1.00N)
6) The mass of the Titanic was 4.6 x 107 kg. Suppose the magnitude of the gravitational force exerted by the
Titanic on the fatal iceberg was 61 N when the separation distance was 100 m. What was the mass of the
iceberg? (2.0 x 108 kg)
7) The Moon has a mass of 7.35 x 1022 kg and its equatorial radius is 1.74 x 106 m. Earth’s mass is 5.97 x 1024 kg
and its equatorial radius is 6.38 x 106 m. Calculate the magnitude of the gravitational force exerted by
i)
the Moon on a 100-kg astronaut standing on the Moon’s surface (162 N)
ii) Earth on a 100-kg astronaut standing on Earth’s surface (978 N)
iii) Explain why the values of Fg in part (i) are different from (ii).
8) Suppose the equatorial radius of Earth was the same as the Moon, but Earth’s mass remained the same. The
Moon has an equatorial radius of 1.74 x 106 m. Earth’s mass is 5.97 x 1024 kg and its equatorial radius is 6.38
x 106 m.
i)
Calculate the gravitational force that this hypothetical Earth would exert on a 1.00-kg object at its
surface. (132 N)
ii) How does the answer in part (a) compare to the actual gravitational force exerted by Earth on this
object? (9.78N; 13.4 times greater)